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effects of valve timing
Discussions appear from time to time regarding a couple of items:
1) Loss of Fifth gear Nut.
2) Engine bucking at low rpm.
I have cured these problems on my 98.5 24 valve by adjusting the valves. Yes, the engine manuals and expert advice indicate this is not necessary. Well, it isn't for the engine to run properly.
However, when the valves are adjusted to all be the same then valve timing is also the same at every cylinder. The effect of this adjustment is that each piston pushes evenly on the rotating crank. I think I remember I adjusted each valve for a mid-range spec setting.
I have 196,000 miles most of which was pulling 15,000 lbs. Since the valve adjustment (approx. 25K miles ago) I have pulled hard well below 1800 rpm without a loose nut (other than the one behind the wheel).
I also can run as low at 1000 rpm without any bucking or hesitation. With idle set at around 850 rpm I think that is pretty clear indication the engine is properly adjusted. I don't pull hard at that low rpm. In my town, Yerington, NV most folks only drive 20 mph in town. Fourth gear seems to do that just fine.
I think valve timing is a subtle, but important, perform element that is usually overlooked.
Rob
Yerington, NV
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